Bathymetry and Elevation

Multi-beam echosounders

High-resolution bathymetric data were collected over the region of the partially-submerged Tongan volcano Hunga Tonga - Hunga-Ha'apai. The data were collected on the RV Tangaroa between April 11, 2022 and May 20, 2022 following an eruption in January 2022 which caused an unusual local tsunami and seafloor telecommunications cable break. The aim of the data collection is to determine whether local tsunami waves and seabed cable faults were caused by secondary submarine landslides or other processes and will characterise the locations, dynamics and magnitudes of these landslides. High-resolution bathymetric data were collected using an EM302 hull-mounted multi-beam echosounder and TOPAS sub-bottom profiler. The data were then compared with existing high-resolution data from before the eruption, allowing for identification of seafloor changes. Data were collected as soon as feasible after the eruption in order for them to be accurate and useful, given the dynamic nature of the seafloor. Multi-beam echosounder data were generally of very high quality. TOPAS sub-bottom profiler data were good quality in lower-lying areas of low relief, however, penetration is poor or absent on steeper slopes and the data are of poor quality in those areas. Raw multibeam data were cleaned and processed using MD-System onboard the RV Tangaroa and gridded into 50 m bins. Geoacoustics TOPAS sub bottom profiler data were acquired along tracklines from the RV Tangaroa. Data were funded by Natural Environment Research Council (NERC) Grant NE/X00239X/1 held by Dr Mike Clare of the National Oceanography Centre (NOC) with collaboration with the National Institute of Water and Atmospheric Research (NIWA).

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